The invention discloses an energy storage unit multi-serial-port communication protocol real-time analysis system and an analysis method thereof. The system is applied to the upgrading and reconstruction process of the energy storage unit, and can analyze the messages of the serial port communication equipment behind an old in-situ control unit and a monitoring system, sort the specific conditionsof old and old communication protocols, and adopts to a new equipment new communication protocol building foundation. The system comprises a communication message capturing device and a message parsing terminal; the communication message capturing device comprises a communication interface converter, a serial port monitoring device and a USB Port HUB, and the message parsing terminal comprises astorage module, a parsing module and a display module. According to the invention, the communication message capturing device is adapted to the non-standard communication serial port of the old in-situ control unit, and the message analysis terminal identifies and analyzes the specific format and content of the communication message so as to record the specific format and content, so that data support is provided for further transformation of the energy storage unit.